For both black and color prints, a small particle size toner is known to improve the image quality of the prints. High speed black and white printers require toner particles that can provide a matte finish in an oil-less fuser system with a low minimum fixing temperature (MFT) to enable high speed printing and at the same time achieve superior image quality in the resultant printed product.
It is known that toners containing carbon black or other conductive pigments are susceptible to inductive charging in high electric fields. As a result, a large amount of wrong-sign toner is created which leads to excessive background on the photoreceptor especially with machines employing contact dual-component development. This inductive background has low transfer efficiency and causes two fundamental problems: poor image quality due to some background toner transferring onto the media, and excessive amount of wasted toner, since most of the un-transferred background toner is directed straight to the waste bottle. Under the most severe conditions, as much as about 80% of the total toner consumed can be lost to inductive background.
U.S. Pat. No. 6,447,974 describes in the Abstract a process for the preparation of a latex polymer by (i) preparing or providing a water aqueous phase containing an anionic surfactant in an optional amount of less than or equal to about 20 percent by weight of the total amount of anionic surfactant used in forming the latex polymer; (ii) preparing or providing a monomer emulsion in water which emulsion contains an anionic surfactant; (iii) adding about 50 percent or less of said monomer emulsion to said aqueous phase to thereby initiate seed polymerization and to form a seed polymer, said aqueous phase containing a free radical initiator; and (iv) adding the remaining percent of said monomer emulsion to the composition of (iii) and heating to complete an emulsion polymerization thus forming a latex polymer.
U.S. Pat. No. 6,413,692 describes in the Abstract a process comprising coalescing a plurality of latex encapsulated colorants and wherein each of said encapsulated colorants are generated by miniemulsion polymerization.
U.S. Pat. No. 6,309,787 describes in the Abstract a process comprising aggregating a colorant encapsulated polymer particle containing a colorant with colorant particles and wherein said colorant encapsulated latex is generated by a miniemulsion polymerization.
U.S. Pat. No. 6,294,306 describes in the Abstract toners which include one or more copolymers combined with colorant particles or primary toner particles and a process for preparing a toner comprising (i) polymerizing an aqueous latex emulsion comprising one or more monomers, an optional nonionic surfactant, an optional anionic surfactant, an optional free radical initiator, an optional chain transfer agent, and one or more copolymers to form emulsion resin particles having the one or more copolymers dispersed therein; (ii) combining the emulsion resin particle with colorant to form statically bound aggregated composite particles; (iii) heating the statically bound aggregated composite particles to form toner; and (iv) optionally isolating the toner.
U.S. Pat. No. 6,130,021 describes in the Abstract a process involving the mixing of a latex emulsion containing resin and a surfactant with a colorant dispersion containing a nonionic surfactant, and a polymeric additive and adjusting the resulting mixture pH to less than about 4 by the addition of an acid and thereafter heating at a temperature below about, or equal to about, the glass transition temperature (Tg) of the latex resin, subsequently heating at a temperature above about, or about equal to, the Tg of the latex resin, cooling to about room temperature, and isolating the toner product.
U.S. Pat. No. 5,928,830 describes in the Abstract a process for the preparation of a latex comprising a core polymer and a shell thereover and wherein the core polymer is generated by (A) (i) emulsification and heating of the polymerization reagents of monomer, chain transfer agent, water, surfactant, and initiator; (ii) generating a seed latex by the aqueous emulsion polymerization of a mixture comprised of part of the (i) monomer emulsion, from about 0.5 to about 50 percent by weight, and a free radical initiator, and which polymerization is accomplished by heating, and, wherein the reaction of the free radical initiator and monomer produces a seed latex containing a polymer; (iii) heating and adding to the formed seed particles of (ii) the remaining monomer emulsion of (I), from about 50 to about 99.5 percent by weight of monomer emulsion of (i) and free radical initiator; (iv) whereby there is provided said core polymer; and (B) forming a shell thereover said core generated polymer and which shell is generated by emulsion polymerization of a second monomer in the presence of the core polymer, which emulsion polymerization is accomplished by (i) emulsification and heating of the polymerization reagents of monomer, chain transfer agent, surfactant, and an initiator; (ii) adding a free radical initiator and heating; (iii) whereby there is provided said shell polymer.
U.S. Pat. No. 5,869,558 describes in the Abstract dielectric black particles for use in electrophoretic image displays, electrostatic toner or the like, and the corresponding method of manufacturing the same. The black particles are latex particles formed by a polymerization technique, wherein the latex particles are stained to a high degree of blackness with a metal oxide.
U.S. Pat. No. 5,869,216 describes in the Abstract a process for the preparation of toner comprising blending an aqueous colorant dispersion and a latex emulsion containing resin; heating the resulting mixture at a temperature below about the glass transition temperature (Tg) of the latex resin to form toner sized aggregates; heating said resulting aggregates at a temperature above about the Tg of the latex resin to effect fusion or coalescence of the aggregates; redispersing said toner in water at a pH of above about 7; contacting the resulting mixture with a metal halide or salt, and then with a mixture of an alkaline base and a salicylic acid, a catechol, or mixtures thereof at a temperature of from about 25 degrees C. to about 80 degrees C.; and optionally isolating the toner product, washing, and drying. Additional patents of interest include U.S. Pat. Nos. 5,766,818; 5,344,738; and 4,291,111.
The disclosures of each of the foregoing U.S. patents are hereby incorporated by reference herein in their entireties. The appropriate components and process aspects of the each of the foregoing U.S. patents may be selected for the present compositions and processes in embodiments thereof.
There remains a need for an improved toner composition and process which overcomes or alleviates the above-described and other problems experienced in the art. There further remains a need for a toner composition suitable for high speed printing, particularly high speed monochrome printing that can provide excellent release and hot offset characteristics, minimum fixing temperature, and suitable small toner particle size characteristics.